Here is the best place to get the manifolds. Probably the best price too.
http://www.designengineering.com/catalog/spa-turbo-usa/turbo-manifolds/chevy
A T3 will probably work fine on the little 230. I prefer a T4 for 250 and 292. They allow more choices for exh housing and turbine sizes.
Snowman has just done this to his car using a 292 truck manifold and cheap Chinese turbo parts. Worked good till the stock shortblock decided not to play.


Inliner Member 1716
65 Chevelle Wagon and 41 Hudson Pickup
Information and parts www.12bolt.com